I've done these calculations since my childhood as a Boy Scout and this has been the best, clearest explanation of the exactness of solar timing I've ever come across. Very nice, simple, and exact. Thanks!
I highly recommend the PBS program "In Search of Longitude". It tells the story of John Harrison, Captain James Cooke etc. A very informative documentary.
Understanding these concepts is all the evidence anyone needs to prove the earth is not flat. I’m amazed that there are people who still chose to argue the point, when anyone with a homemade protractor can demonstrate the proof.
@@alphagt62 I hate to butt in on your comment but---, just a thought, the leader of "The Flat Earth Society" who died recently knew the Earth was a sphere. Remember how he fell out of a homemade rocket? Kool. His family said his claims were to gain recognition & make money, which is what I suspected all along. As to his followers, I suspect that most of them think along the same lines & they make these claims by way of a joke. Some people make counter claims on any argument in order to "stand out". I've known a few. Some though, probably actually believe that the Earth is flat. I can't quite analyze them other than extreme ignorance. I'd like to know what percentage of Flat Earthers actually believe it?
@@robertsansone1680 I’ve had much the same thought. I suspect most of them know the earth is round, and they choose to be contrary. You see them fudge experiments trying to prove their point, so they must know, right? But, I also know that a lot of their followers are steadfast believers! They will hear nothing to the contrary, and of course when questioned their first response is, “Prove it”. Thinking that no one without a space ship can prove it. But there’s the North Star, always in the same spot, and referencing it from any spot on Earth shows a sphere. And the fact if you go below the equator, it goes below the horizon. If the Earth were flat, that could never happen. But to these hard core believers who are not just spoofing everyone, it is my belief they suffer from mental delusions. They suffer paranoia, their need to believe someone is trying to fool them is stronger than their ability to weigh the evidence.
John Harrison was a cabinet maker by trade, so not only was he not taken seriously by the admiralty but he also had to teach himself the intricacies of working with metals and all the tolerances that went with it. A truly amazing master of his time. Pun not intended.
My 4x great grandfather was first surveyor hire by Hudson’s Bay company in late 1700’s. His work has been verified to e a few degrees off. A ocean away in a raw country, just a sextant and mercury as a mirrors and all math done by hand. It would take him up to six hours for just one point. Wow. His story can be told I. Book, Mapmaker, good read.
It is very much "too easy" to ignore the difficulties the industry and the brilliance of those who have gone before. My respects sir, to you and to your four times great-grandfather. Vastly more people than those who choose to acknowledge it, are greatly indebted to your four times great-grandfather, and others of his calling and ilk ..................
I watched 3 youtube videos with young youtubers who were only yelling and joking, not explaining it properly. Now I finally found this video and I can finally understand it, thanks for that!
Excellent video! Thank you very much! As a septuagenarian retired pilot I was able to see many advances in navigation aids and always appreciated our predecessors and what they went through. You've really made appreciating their knowledge and efforts easier to grasp. Again, thanks!
Finally, a proper and clear description of calculating longitude. Going through all the other sites and videos on this subject has been unbelievably painful. Thank you !
Thanks for putting this together! I’m a surveyor and these days we use positional data provided by computers. I can’t wait to try this out and do some “real” old school surveying.
I totally enjoyed this video... At almost 69 years of age, I finally have a pretty damn good idea how all this is measured/calculated. Thank you very much!
Fascinating. In the movie Jeremy Irons plays the guy who had to restore Harrison's clock. He discovers it was like navigating a maze. Apparently whenever Harrison tried something which didn't work, he didn't undo it and try something else, instead he built a new mechanism to overcome the problem created by the first. So layers and layers of complexity were built up one on top of another. Is it a coincidence that watchmakers still call additional mechanical features "complications"?
I had to Teach myself Celestial Navigation. After stumbled through half a dozen different books, which were little help, I finally found George Mixter! His book: "Primer of Navigation" from 1940 explained everything in clear, practical terms. And I've been a Wiz ever since!
Excellent video, thank you for the demonstration and animations. There is one thing I would add - how to determine your time zone. Your marine chronometer would be set to Greenwich time. Therefore wherever you are, you only need to take the time of solar noon, calculate the difference from 12:00pm, and then multiply by 15 degrees. I.e. the clock tells you your time zone.
@Mr22Guy exactly. This video only demonstrated how to verify your time zone and longitude. It was not a how-to on determining where you're at in the world without knowing what time zone you were in.
He would have been even more accurate if his sundial was bigger with a precise tip and measured more frequently, so that you could be determine when exactly solar noon occurred. You don't really need accuracy of less than a kilometre for navigation of such scale that you need to know longitude anyway.
If you consider a modern time-keeping device "simple equipment" you'd be in for a shock if you ever found yourself back in the 18th century. Simple to use, yes. But making them has taken humanity many millennia of standing on the shoulders of giants.
I spent 20 Years teaching Navigation. Once asked a guy to tell Me where We were. After a few Minutes of studying his Map and Compass he pointed to a slight rise in the ground a few Metres away and Proudly Announced "We're over there".
Good for him!. I truly end up going the exact opposite to desired direction. Learned the sun's position helps me detect west from east and then get my bearings, turn around and head off in the right direction. A work in progress...
The information given was tip top. I'm too old school to listen to someone annihilate a simple word. He could have said parallel. I could have watched kittens meeting the family dog for the first time. Having said that; I carry around a device that pin points my location with 21st century accuracy
@@kellytaylor9084 I can never remember in which way the sun goes - was it west to east or east to west. I have to look it up everytime - it's hopeless.
I love the story of John Harrison and his clock, his discovery and how he had to beat his detractors. This presentation is very enlightening, thank you.
I hate the story for the sub-human meanness of the "officials" involved. Bloody bastards, may they burn in Hell for the hardship they put that genius through.
This was great! I've always wondered this process, never more so than re-rereading the incredible adventures of Douglas Mawson, Scott, and Shackleton. Your explanation was brilliant! Thank you!
Thank you. This is one of the most outstanding presentations I have watched on TH-cam: crystal clear, word perfect, a joy to watch! It is amazing what a gifted, intelligent teacher can achieve!
Great video. To those interested in John Harrison’s story the man who invented the maritime timekeeper watch this period movie called Longitude 2000 UK movie. Brilliant acting brilliant telling of inspiring story of resilience
A few years ago, I emailed Dava Sobel and she was kind enough to reply with interesting observations. Lovely to see her book recommended here. Fascinating post thanks a bunch. I spent years flying and looking at inertial navigation systems and GPS update INS so it's good to see (again) the theory so simply explained.
Outstanding video. I'm always fascinated by WIlliam Clark's (as in Lewis and Clark) cartography. Using nothing but dead reckoning while they traveled from St. Louis to what is today Astoria Oregon, his estimate of miles was within seventeen or eighteen miles after a trip of something like 3700 miles of river and hiking travel.
Great video, as always. I just finished the book "Longitude" you mentioned, too, and concur--heck of a read. Thank you for combining hands-on projects with historical science.
Yes, as a devotee of John Harrison and gazed at the real Harrison clocks at Greenwich this is the best explanation I have ever experienced of finding longitude. Thank you
Spent twenty three years navigating ships using the stars, sun, and dead reckoning. Would use the sun and time to get LAN (local apparent noon). Your theory works but I have never heard lon gi tude pronounced as you do. LONG I TUDE?
In about 1990 the department of harbours and marine in Brisbane surveyed Moreton bay using differential GPS and modern depth sounders. The bay was previously mapped by Mathew flinders in the late 1700s using the methods of the time . They found that Flinders charts were accurate to within one decimeter (approx 4 inches .) Not bad for a guy using lead-lines for soundings and a sextant and clock for positioning .
Neueregel Harrison's genius was as a master craftsman who invented a highly accurate timepiece capable of operating in a marine environment where ships are being tossed about. The scientists and mathematicians of the time contemptuously dismissed his work as it didn't involve sophisticated mathematical calculations of which they were so fond. It turned out that Harrison's chronometer not only resulted in more accurate calculations of longitude, but simplified the mathematics involved.
If you think its amazing that someone from 300 years ago was so smart Neueregel, look into the ancients like Pythagoras. What he knew and did will really blow your mind.
Huge Bartlett "If I recall correctly,he was swindled out of his reward by the king..." Nope: he was swindled by the Board of Longitude because they didn't like a non-scientist doing what they couldn't. King George III intervened on Harrison's behalf, after testing Harrison's 2nd watch (H5) himself and finding it to be extremely accurate. Under pressure from King George, Parliament awarded Harrison the sum of £8,750, but the Board never officially acknowledged his success, and never awarded the Longitude Prize to anyone. (In addition to the £8,750 awarded by Parliament, he had already received £4,315 in increments from the Board for his work, and £10,000 as an interim payment for the first watch (H4), which together with the £8,750 awarded by Parliament was actually more than the £20,000 prize would have been. It was a long time coming, but the final decade of his life was spent as a wealthy man.)
As a Geography enthusiast, I have done these calculations before and was reasonably accurate. This is an excellent tutorial video. Thanks. 34,31/-93,2.
Excellent work. Seeing you do it in the calm of your garden only makes me more in awe of the sailors who managed to do it on a pitching sailing vessel.
I can't tell if you're trolling or not. I could only listen to about a third of this because the mispronunciation of word longitude was making my head hurt
That was the best explanation of calculating longitude that I have seen. So much so, that I understood it for the first time (and I watched the TV series).
The US Navy is retraining officers to use this navigation method in addition to basic seamanship. Due in part to the number of accidents and collisions at sea, another concern is the vulnerability of GPS based systems to hostile hacking. I recently read an article where the best training for this is the Royal Navy- one reason there will always be an England.
Nice video, but why confuse the example with a reference to Eastern time zone (a piece of info not available during the Age of Discovery)? It seems clearer to illustrate that a navigator sets his clock to Greenwich mean time when he leaves port and calculates his longitude by noting the time at which the sun is at its zenith (and multiplies the hours past noon by 15 to get the longitude).
Agreed, was trying to noodle it thru then just said, "solar noon difference from my GMT set watch". Read the comments to make sure I was correct. Thanks!
Craig M You`re right, and to achieve this, we must have a second clock that we start when the Greenwich clock indicates noon. This second clock is stopped when the sun culminates. From the duration measured by this second clock, we calculate the longitude.
I have already read Longitude by Dava Sobel, and you are right; it is truly an amazing story. It’s remarkable to consider how many people opposed John Harrison's efforts. He dedicated a significant part of his life to this project.Thank you for your video. Most enjoyable and clearly explained.
0:14 In case people are wondering, at the start of the video, that's a detail of the sculpture at the Belém Tower (Torre de Belém) in Lisbon, Portugal.
Yep. I immediately recognized it. I was stationed in Lisbon for two years with NATO. Drove past the Tower many times. The Portuguese were certainly great explorers.
I didn't finish what I wanted to say about his mispronunciation of longitude. What happens is, that word will be mispronounced by thousands who will pass it on and on and on. Look what's happening to a simple word like tour.
I like your effort and your video very much. I would suggest a simpler technique to present to students: First, set the watch to GMT (of UTC, if you prefer that terminology). Then, determine the GMT (watch time) of solar noon using the method in your video. The difference between GMT and 12:00 (solar noon), in hours and decimal fractions of an hour, times 15, is your rough longitude. You could then apply the Equation of Time value for your particular date as you describe in this video to refine your longitude figure.
Absolutely the best explanation and a practical demonstration of how to find a longitude position based on a chronometer set to GMT, and a needle casting a shadow on a sunny day. Even I understood the science behind it. Thank you.
But how do you determine your longitude when you are for example in the middle of the ocean and do not know your position at all. That is exactly what you want to find? And what role does the chronometer play in this. This video unfortunately does not provide an answer to this... Where can I find an answer to this?
Only two marks are enougth to find solar noon Put mark at 10:30 and draw circle arc from it using pin as center. Then wait until shadow touches this arc at evening (shadow is same length as at 10:30) Put second mark. Draw an line between marks an find the middle point on it. Line between pin top and that middle point will be precisely south-north aligned. Time when shadow points to south (or north if you're in Southen hemisphere) you can calculate easily - it is a middle of time range between timestamps of two marks on arc
Yes. That was one of the Boy Scout methods of finding true north. At the moment the shadow points true north is also local solar noon. Idiots in the disUnited states are contemplating permanent daylight savings time, basically moving everything 15 degrees east. Local solar noon would be 1100 rather than 1200 (approximately).
Nice treatment of the subject. I used two nails oriented perfectly N/S and recorded the time of perfect shadow alignment. This of course required a perfect N/S line. Then I applied the equation of time as you did. I like your method better. ;-)
This is a great video. I think it would have been better at 7:02 to demonstrate longitude calculation from solar noon as they had done in the past at sea. i.e. set your watch to Greenwich Time, as they would have done before leaving port in England. Then you wouldn't have to explain that you are in America which is 5 hours behind etc... prior knowledge you wouldn't have if you were lost at sea.
That is the reason he said chronometer dude... a watch measures time where you are a chronometer keeps time elsewhere it is the comparison of solar noon at TWO different LOC's at the SAME TIME that allows us to use this constant to determine the distance (a variable as you travel N & S from equator to poles) in an E- W or W- E direction... it is precisely because of this fact that a clock-maker was the one to solve the riddle... you can't measure the variable distance directly.... but you can measure the constant of the earths travel around the sun... a time solution to a variable distance problem!
I was a squad leader in the Army and taught land nav to young soldiers. Many couldn’t read a map if there life depended on it. Without a cell phone they would be in trouble.
Cell phones didn't have GPS when I was in... which is why I would bring a Garmin eTrex! With few exceptions people live and fight in cities so arguably aerial imagery is more important than topo maps. SF probably has the most need for traditional orienteering/land nav and they'll use GPS if available.
I read in Navy Times last year, that the Navy is going back and teaching their officers how to navigate this way as they used to do with a Sextant. The reason was a good one too. In case their navigation satellites get taken out by the enemy.
Take it easy Scotch Terrier. We are all here because we like to learn things. No need to snap at the guy. He had a valuable contribution to make to the conversation. @@Scottie1152
Im glad you put some perspective in there. The fact a small error (to most people) can give you a 80km variation really drives home how precise you need to be.
Oh Yeah !! Too bad it could of offered some practical information, but left out a very important detail ! This world is STATIONARY and FLAT !! SORRY TO CAUSE YOU A LITTLE DISTRESS !!!!!
Jim Petosa Don't worry...I think they're just a bunch of trolls, with maybe a few mistaken and ignorant extremists they allow among them for appearances.
@@brianharrigan8821 No distress Brian, just one question. If the world is flat as you reckon, and North is North, Why cant i see Polaris (The North Star) from my place on this globe? I'll leave it to you to reply before i tell you where i live :) Peace. Ps. No need to raise your voice( CAPS) it makes you appear desperate and forceful and in a panic to make people see your way. Peace.
Reaper4367 flatards and fundys have a belief and then invent evidence to support their beliefs, the opposite to science, observation and reason and logic... blah blah blah... nothing wrong with skepticism... science changes as it grows unlike ridiculous beliefs...’ it is easier to fool someone than to convince someone they are wrong....’ have a great day....
@@brianharrigan8821 What would be the difference if the earth was stationary and the stars were moving? There would be no difference in the calculation. If you weren't taught that the earth was moving, you would think the stars are moving. Example; you may have run across this before...this happened to me which made me think about the problem of which is moving. You are sitting in your car at a red stop light. You aren't really paying too much attention, you're just waiting. The next thing you know, you are rolling backwards; you push harder on the brakes but that doesn't help. you think your brakes are failing. Then you realize the car next to you is inching ahead and you are not moving at all. This whole scenario takes about 5 seconds. Because the only reference point was the car beside you, you can't tell which is moving. So if you were taught that the stars were moving and the earth is stationary, you could believe that as you can't feel any movement. It all depends on what you were taught in this case. That's why the ancient civilizations, who built the mega structures, that we can't duplicate today, proves they were not stupid but highly intelligent and they believed the earth was still and the stars were moving. You would too except someone told you different and because you think they are more intelligent than you, you believed the first thing you heard as being true. Santa is not real to you today (I'm assuming) BUT HE WAS because someone told you he was. Then someone told you he wasn't and so now he's not. Why do you believe one and not the other when you can't prove either. You yourself can't prove the earth is round, you are relying on the information you're given and if you believe that your government doesn't lie and NASA isn't lying, then the earth is round. However, we know now that there is great controversy in the scientific community because many things NASA is stating are not adding up, just as scientists and engineers in many countries are finding many problems with the so called "facts" that planes brought down the Twin Towers and an invisible plane must have hit the Pentagon because they can't find any plane parts, bodies, seats or luggage. So believe what you want if you trust the information is true and the only way to find the truth is to look at EVERYTHING whether you believe it or not and try to find out why others believe what they do. Test both sides if you want the truth and listen to nobody. Just because something is popular, doesn't mean it is true; it just means it's popular, today; but somewhere down the road something else may take its place because more evidence has surfaced. Think of how many times scientists have been wrong. I don't know if the earth is flat or round because I haven't seen it but what I do know, is that NASA and Al Gore are liars and you can take that to the bank.
I agree, pronunciation is variable. Great video this!. His recommendation about Dava Sobel's Book is a good one, it is a fantastic story of struggle and endeavour. I was born in Rochester Kent (England) and there is a link between the Longitude story and the drive to seek a solution to the problem. That reason is a clock that still hangs above the Corn Exchange near Rochester High Street was donated by Sir Cloudesley Shovell, (one time Mayor of Rochester and English Admiral) who in 1707 lost his life and four warships plus est 2,000 lives in a storm off the Scilly Isles. One major factor in the disaster was reckoned to be lack of accurate position knowledge by navigators. This lead the British Admiralty to seek ways of better determining the position on the globe. In turn this lead to 'The Longitude Act of 1714' and in turn the competition was on to devise the best seaworthy chronometer. I believe the whole thing took several decades.
Excellent video doing what real teachers do--make the complex accessible if not simple. BTW, the man is Canadian as his pronunciation of other words makes clear. Canadians are too polite to point out ignorant boors in the comments section who don't understand that there are many perfectly correct dialects of English in the world.
That was an excellent and fascinating video. Your use of graphics to demonstrate what was going on was masterful. Thanks for taking the time to produce this video. I have added it to my favorites list.
In the comments section it seems once more that English speaking persons think they invented language itself. Nothing wrong with the pronunciation of "longitude". The pronunciation of "data", however, is questionable. But I would rather acknowledge the video of this dude.
I did this experiment about 10 years ago, using a quadrant (latitude), and watch (longitude). The chart for equation of time and declination, was available in an old air force survival manual. At the time there was no TH-cam videos, so I made one, but needed to correct some things to make it easier to understand. Never got around to re uploading, but I love this video. Very clear and good instructions. Thank you!
@@Jimwill01 It is PATHETIC. Can you imagine what this world will be like when these are the people running things? They don't even teach cursive in America. I've asked lawyers "What's going to happen when these people can't read the founding documents of this country?" They don't even know how to answer.
But how do you determine your longitude when you are for example in the middle of the ocean and do not know your position at all. That is exactly what you want to find? And what role does the chronometer play in this. This video unfortunately does not provide an answer to this... Where can I find an answer to this?
Wonderful ! I was a Geography major in College, so this is very interesting to me. Longitude I knew was time based. I have often timed the Moon’s progress across the sky. I figured out why there was 360 in a circle, and why there is 24 hours in a day ( stick and string, radius, and 12 points, etc) 60 minutes in an hour, etc. Primitive, I know, but so revealing why things are the way they are. Thanks!
Very nice. But the use of the clock is not explained clearly. I imagine sailers set out from “Greenwich” and set their clock at 0:00 or 12:00. They did not change this during their voyage. In other words, they carried Greenwich time with them. At any point on earth they knew what time it was in Greenwich. A precise clock was thus of paramount importance.
It's nice to see this wrapped up in a short and straightforward video. A couple years ago, I purchased a sextant and book on celestial navigation. I also have a book on using the sextant. It is a remarkably elegant instrument. In the hands of an expert, the sextant I got, a Davis Mark 25, the vernier drum is marked to 2 MOA. That's equivalent to two nautical miles by definition. I imagine an expert can improve on that with multiple readings. This is certainly good enough for crossing the Atlantic because it lands you in line of sight of your port of call.
I never understood what role clocks (chronometers) played in navigation but I knew it was key. This video really cleared that up. Amazing, thanks science online :) That's been niggling at me for ages
Excellent video, clear and concise. Today's high school students should turn off their phones and get out in the sun with a clock! And the ancient mariners calculated latitude and longitude on the rolling deck of a square rigger. Now that's true seamanship!
From 1971 onward my best friend was the grandson of the inventor of the Weems system of navigation. I'm recalling countless sextants and other such gear, learning the basics of use. Captain Phillip V.H. Weems, USN retired had invented the system which, I was told, was in use on Apollo 11. Really amicable and brilliant man, he'd ridden on horseback from Clarksburg, Tennessee to attend the US Naval Academy in Annapolis, Maryland. I think I was in 7th grade/age 12-ish when I first met him. As we sat eating breakfast, hearing wonderful stories of his travels and youth, he'd pushed his plate aside, eating from my plate; a little dementia evident, but what a life of achievements. I know a land surveyor who uses Weems' equipment in celestial navigation methods.
In case anyone is confused by the pronunciation of *longitude,* you should know there are two common ways to pronounce the work. The narrator was actually using the UK pronunciation even though he lives in the US. Thanks for the interesting video.
I've been reading some of the comments and I have a question. How many times do I have to do a head dive into an empty swimming pool before I start to see and understand the logic of the flat earthers?
It's 3 actually...The same as "The Number Of licks it takes To Get To The Center Of A Tootsi-Roll Pop", according to some "Wise Old Owl" th-cam.com/video/IBwJHXqryh0/w-d-xo.html
@@FemboyEngineerno reason ? Ppl 4 hundred years ago figured out that the earth is round , today with the advanced technology we have now we actually have ppl arguing a subject that was resolved hundreds of years ago . So no good reason ? 😂 They should be laughed at for challenging something for just the sake of challenging something
@@easternsuneasternsun171 um, actually, no. People did not prove the Earth was round 400 years ago. That’s a bit silly to think it took us that long. It was proven about 2,500 years ago by the Greeks by measuring distances, celestial bodies, and light and shadows. They even accurately calculated the circumference (how big it is, calculating the distance it would take if you traveled all the way around in a straight line and back to where you began). Eratosthenes’ estimate was only about 300 miles short of the actual circumference. I think you were referring to circumnavigation, sailing around the world. It isn’t necessary to circumnavigate to prove the earth’s roundness. People think Columbus proved the earth was round. He didn’t. A flat earther would argue that by reaching the Americas he simply showed that the planet is larger than previously imagined. It was actually Magellan who first sailed around the world. Again, this didn’t prove the earth was round (I mean, yes, it is another bit of evidence for it) because it was already known to be round and sailing coordinates were estimated based on the model of a round earth.
Interesting you say LONG uh too d. I've always said LONJ uh too d. I read the book long ago and there was a great PBS series on this. I think that this should be taught for a couple of days in high school. Maybe even before geography..which I guess they don't teach anymore :-( Great presentation. I recently visited the Lewis and Clark museum near me and they had a demo of how they would find their location using the mercury method and sextant. Noon sights of course, for the most part.
Finally. Someone asked why he pronounces "longitude" the way he does. I, too, have always heard it pronounced "lonJ-ih-tude." I wish the creator of the video or someone else had responded to you. Nothing I found in a quick search via Duck Duck Go explains it. It creates the impression of incompetence, making the listener slightly skeptical that he really knows what he is talking about. Yes, (at anyone misreading what I just wrote) he IS competent and demonstrates this, but, the mispronunciation (or odd and unusual pronunciation
I've done these calculations since my childhood as a Boy Scout and this has been the best, clearest explanation of the exactness of solar timing I've ever come across. Very nice, simple, and exact. Thanks!
I highly recommend the PBS program "In Search of Longitude". It tells the story of John Harrison, Captain James Cooke etc. A very informative documentary.
Hey John my scoutmaster explained it to us too!
Understanding these concepts is all the evidence anyone needs to prove the earth is not flat. I’m amazed that there are people who still chose to argue the point, when anyone with a homemade protractor can demonstrate the proof.
@@alphagt62 I hate to butt in on your comment but---, just a thought, the leader of "The Flat Earth Society" who died recently knew the Earth was a sphere. Remember how he fell out of a homemade rocket? Kool. His family said his claims were to gain recognition & make money, which is what I suspected all along. As to his followers, I suspect that most of them think along the same lines & they make these claims by way of a joke. Some people make counter claims on any argument in order to "stand out". I've known a few. Some though, probably actually believe that the Earth is flat. I can't quite analyze them other than extreme ignorance. I'd like to know what percentage of Flat Earthers actually believe it?
@@robertsansone1680 I’ve had much the same thought. I suspect most of them know the earth is round, and they choose to be contrary. You see them fudge experiments trying to prove their point, so they must know, right? But, I also know that a lot of their followers are steadfast believers! They will hear nothing to the contrary, and of course when questioned their first response is, “Prove it”. Thinking that no one without a space ship can prove it. But there’s the North Star, always in the same spot, and referencing it from any spot on Earth shows a sphere. And the fact if you go below the equator, it goes below the horizon. If the Earth were flat, that could never happen. But to these hard core believers who are not just spoofing everyone, it is my belief they suffer from mental delusions. They suffer paranoia, their need to believe someone is trying to fool them is stronger than their ability to weigh the evidence.
John Harrison was a cabinet maker by trade, so not only was he not taken seriously by the admiralty but he also had to teach himself the intricacies of working with metals and all the tolerances that went with it. A truly amazing master of his time. Pun not intended.
My 4x great grandfather was first surveyor hire by Hudson’s Bay company in late 1700’s. His work has been verified to e a few degrees off. A ocean away in a raw country, just a sextant and mercury as a mirrors and all math done by hand. It would take him up to six hours for just one point. Wow. His story can be told I. Book, Mapmaker, good read.
It is very much "too easy" to ignore the difficulties the industry and the brilliance of those who have gone before. My respects sir, to you and to your four times great-grandfather. Vastly more people than those who choose to acknowledge it, are greatly indebted to your four times great-grandfather, and others of his calling and ilk ..................
I tried to find the book but I didn't understand how you wrote the title
@@XXX-tw6zm it’s called Mapmaker, I made a typo, should of read…..can be told in the book Mapmaker, it’s written bu Barbra Mitchell.
Yes!!!!! Hand watch , see and record ….!!!!
One of your 32 great, great, great, great grandfathers.
This gentleman is a very good narrator and explained his subject so well. His speech is clear and evenly paced, well done.
Never heard it called longitude with a HARD g.
I have. Many times but more often in the UK
I watched 3 youtube videos with young youtubers who were only yelling and joking, not explaining it properly.
Now I finally found this video and I can finally understand it, thanks for that!
Aah,the joys of old youtube,when things were posted just to share information,not for clout or money.
A very well-illustrated explanation for determining longitude. This former sailor approves!
this sailor approves too...very simple explanation to something seemingly complex
This old beat up former Army Ranger Pathfinder approves as well . ATB
@Mike Jackson : As many times as they wish. More, if they're from Chicago.
@Mike Jackson Only if timid virgins make dull companions.
This Coastie also approves.
Excellent video! Thank you very much! As a septuagenarian retired pilot I was able to see many advances in navigation aids and always appreciated our predecessors and what they went through. You've really made appreciating their knowledge and efforts easier to grasp. Again, thanks!
Glad I found this channel. Simple, not over produced, and spot on. Well done!
Finally, a proper and clear description of calculating longitude. Going through all the other sites and videos on this subject has been unbelievably painful. Thank you !
Thanks for putting this together! I’m a surveyor and these days we use positional data provided by computers. I can’t wait to try this out and do some “real” old school surveying.
I totally enjoyed this video... At almost 69 years of age, I finally have a pretty damn good idea how all this is measured/calculated. Thank you very much!
Fascinating. In the movie Jeremy Irons plays the guy who had to restore Harrison's clock. He discovers it was like navigating a maze. Apparently whenever Harrison tried something which didn't work, he didn't undo it and try something else, instead he built a new mechanism to overcome the problem created by the first. So layers and layers of complexity were built up one on top of another. Is it a coincidence that watchmakers still call additional mechanical features "complications"?
I had to Teach myself Celestial Navigation. After stumbled through half a dozen different books, which were little help, I finally found George Mixter! His book: "Primer of Navigation" from 1940 explained everything in clear, practical terms. And I've been a Wiz ever since!
Excellent video, thank you for the demonstration and animations.
There is one thing I would add - how to determine your time zone.
Your marine chronometer would be set to Greenwich time. Therefore wherever you are, you only need to take the time of solar noon, calculate the difference from 12:00pm, and then multiply by 15 degrees. I.e. the clock tells you your time zone.
@Mr22Guy exactly. This video only demonstrated how to verify your time zone and longitude. It was not a how-to on determining where you're at in the world without knowing what time zone you were in.
Would you use a Sextant to determine that?
This is one of the most interesting videos that I have ever seen. Very well explained. Thank you!
That's remarkable accuracy for such simple equipment. Well done!
He would have been even more accurate if his sundial was bigger with a precise tip and measured more frequently, so that you could be determine when exactly solar noon occurred. You don't really need accuracy of less than a kilometre for navigation of such scale that you need to know longitude anyway.
If you consider a modern time-keeping device "simple equipment" you'd be in for a shock if you ever found yourself back in the 18th century. Simple to use, yes. But making them has taken humanity many millennia of standing on the shoulders of giants.
I spent 20 Years teaching Navigation. Once asked a guy to tell Me where We were. After a few Minutes of studying his Map and Compass he pointed to a slight rise in the ground a few Metres away and Proudly Announced "We're over there".
Good for him!. I truly end up going the exact opposite to desired direction. Learned the sun's position helps me detect west from east and then get my bearings, turn around and head off in the right direction. A work in progress...
The information given was tip top. I'm too old school to listen to someone annihilate a simple word.
He could have said parallel. I could have watched kittens meeting the family dog for the first time. Having said that;
I carry around a device that pin points my location with 21st century accuracy
@@kellytaylor9084 I can never remember in which way the sun goes - was it west to east or east to west. I have to look it up everytime - it's hopeless.
I love the story of John Harrison and his clock, his discovery and how he had to beat his detractors. This presentation is very enlightening, thank you.
Still they denied him the prize money
I hate the story for the sub-human meanness of the "officials" involved. Bloody bastards, may they burn in Hell for the hardship they put that genius through.
@@G0nxsf ...they used his name in the second Star Trek movie as Kahn's alias. Probably coincidence.
This was great! I've always wondered this process, never more so than re-rereading the incredible adventures of Douglas Mawson, Scott, and Shackleton. Your explanation was brilliant! Thank you!
Thank you. This is one of the most outstanding presentations I have watched on TH-cam: crystal clear, word perfect, a joy to watch! It is amazing what a gifted, intelligent teacher can achieve!
That was something I have wanted to know for many years. Thank you kindly for the excellent explanation.
Great video. To those interested in John Harrison’s story the man who invented the maritime timekeeper watch this period movie called Longitude 2000 UK movie. Brilliant acting brilliant telling of inspiring story of resilience
Vassilena Duleva thank you. I'll try to watch that.
I've watched that movie and thoroughly enjoyed it.
Harrison was a perfectionist, he should've taken the prize straightaway with the MK1 model, would've saved a lot of grief.
There is also a great book on John Harrison called Longitude by Dave Sobel. I have read it 3 times now.
The movie is based on Sobel's book.
This is great stuff, I'll have to re watch it when I'm sober. Thank you for your post, I shall return.
A few years ago, I emailed Dava Sobel and she was kind enough to reply with interesting observations. Lovely to see her book recommended here. Fascinating post thanks a bunch.
I spent years flying and looking at inertial navigation systems and GPS update INS so it's good to see (again) the theory so simply explained.
Outstanding video. I'm always fascinated by WIlliam Clark's (as in Lewis and Clark) cartography. Using nothing but dead reckoning while they traveled from St. Louis to what is today Astoria Oregon, his estimate of miles was within seventeen or eighteen miles after a trip of something like 3700 miles of river and hiking travel.
A very lucid and understandable illustration,with a helpful presentation using a true hands-on demonstratio.
Great job, sir!
Very nicely presented. I was trained as a navigator in the Navy. This video would make a great addition to curriculum.
Great video, as always. I just finished the book "Longitude" you mentioned, too, and concur--heck of a read. Thank you for combining hands-on projects with historical science.
Yes, as a devotee of John Harrison and gazed at the real Harrison clocks at Greenwich this is the best explanation I have ever experienced of finding longitude. Thank you
Videos like this are apart of the great ones, good on you. Thank you! This adds value to society!
Nice video. Thanks for posting. In my 60 years, I have never heard longitude pronounced that way.
He's Canadian, eh?
I had to mute it to keep from hearing him...
Spent twenty three years navigating ships using the stars, sun, and dead reckoning. Would use the sun and time to get LAN (local apparent noon). Your theory works but I have never heard lon gi tude pronounced as you do. LONG I TUDE?
See this link : th-cam.com/video/zjbu66pGqJc/w-d-xo.html
In about 1990 the department of harbours and marine in Brisbane surveyed Moreton bay using differential GPS and modern depth sounders. The bay was previously mapped by Mathew flinders in the late 1700s using the methods of the time . They found that Flinders charts were accurate to within one decimeter (approx 4 inches .) Not bad for a guy using lead-lines for soundings and a sextant and clock for positioning .
I would suspect that he used triangulation for anything in line of sight, rather than solar, but your point is valid.
People took GREAT pride in their work; mostly because they had to sign it.
Wait, 4 inches on a map or on land within 4 inches?
@@philgiglio9656 That's why when people post longitude readings under the handle "anonymous," it's never any good.
@@tonycelestro1959 DO NOT INSULT THE MAN. HE DID HIS WORK PAINSTAKINGLY. HE STUDIED MORE MATHS THAN YOU
Cool project, well done. Harrison was a genius, 3 centuries ago, and smarter than most people of today
Neueregel Harrison's genius was as a master craftsman who invented a highly accurate timepiece capable of operating in a marine environment where ships are being tossed about. The scientists and mathematicians of the time contemptuously dismissed his work as it didn't involve sophisticated mathematical calculations of which they were so fond. It turned out that Harrison's chronometer not only resulted in more accurate calculations of longitude, but simplified the mathematics involved.
If I recall correctly,he was swindled out of his reward by the king,and only long afterward received a pittance from the Crown.
If you think its amazing that someone from 300 years ago was so smart Neueregel, look into the ancients like Pythagoras. What he knew and did will really blow your mind.
Huge Bartlett "If I recall correctly,he was swindled out of his reward by the king..."
Nope: he was swindled by the Board of Longitude because they didn't like a non-scientist doing what they couldn't. King George III intervened on Harrison's behalf, after testing Harrison's 2nd watch (H5) himself and finding it to be extremely accurate. Under pressure from King George, Parliament awarded Harrison the sum of £8,750, but the Board never officially acknowledged his success, and never awarded the Longitude Prize to anyone. (In addition to the £8,750 awarded by Parliament, he had already received £4,315 in increments from the Board for his work, and £10,000 as an interim payment for the first watch (H4), which together with the £8,750 awarded by Parliament was actually more than the £20,000 prize would have been. It was a long time coming, but the final decade of his life was spent as a wealthy man.)
As a Geography enthusiast, I have done these calculations before and was reasonably accurate. This is an excellent tutorial video. Thanks. 34,31/-93,2.
Excellent work. Seeing you do it in the calm of your garden only makes me more in awe of the sailors who managed to do it on a pitching sailing vessel.
Quite an amazing and very approachable demonstration, thank you for sharing the wisdoms.
Man, this was _outstanding!_ Simple, clear explanations and great pronunciation! 😀
I can't tell if you're trolling or not. I could only listen to about a third of this because the mispronunciation of word longitude was making my head hurt
Thank you for sharing your knowledge and creating this fantastic video! Its very informative and insightful! Kind regards.
A clear and concise explanation. Fascinating stuff. Thank you for the upload.
That was the best explanation of calculating longitude that I have seen. So much so, that I understood it for the first time (and I watched the TV series).
What an excellent video and demonstration, clear and concise. Thankyou.
The US Navy is retraining officers to use this navigation method in addition to basic seamanship. Due in part to the number of accidents and collisions at sea, another concern is the vulnerability of GPS based systems to hostile hacking. I recently read an article where the best training for this is the Royal Navy- one reason there will always be an England.
Nice video, but why confuse the example with a reference to Eastern time zone (a piece of info not available during the Age of Discovery)? It seems clearer to illustrate that a navigator sets his clock to Greenwich mean time when he leaves port and calculates his longitude by noting the time at which the sun is at its zenith (and multiplies the hours past noon by 15 to get the longitude).
exactly!
Agreed, was trying to noodle it thru then just said, "solar noon difference from my GMT set watch". Read the comments to make sure I was correct. Thanks!
I agree also. Do you have any answers to the questions in my post of today? (28 Sep 2018, 18:07 GMT)
Craig M You`re right, and to achieve this, we must have a second clock that we start when the Greenwich clock indicates noon. This second clock is stopped when the sun culminates. From the duration measured by this second clock, we calculate the longitude.
The second clock's not necessary.
I have already read Longitude by Dava Sobel, and you are right; it is truly an amazing story. It’s remarkable to consider how many people opposed John Harrison's efforts. He dedicated a significant part of his life to this project.Thank you for your video. Most enjoyable and clearly explained.
Very nice. Crystal clear and easy to understand dictation. Thumbs up!
Wish this was 40 minutes long. Calming voice and great & clear presentation. Would buy an audiobook.
Amazing how talented many TH-camrs are. I much prefer watching everyday people like this man over celebrities.
This man has unfortunately passed away since this, but it's inspiring to see a life lived educating others
@@Deathhead68 that is sad to hear, I am happy his personality and wisdom is still being enjoyed after his passing
0:14 In case people are wondering, at the start of the video, that's a detail of the sculpture at the Belém Tower (Torre de Belém) in Lisbon, Portugal.
Yep. I immediately recognized it. I was stationed in Lisbon for two years with NATO. Drove past the Tower many times. The Portuguese were certainly great explorers.
I didn't finish what I wanted to say about his mispronunciation of longitude. What happens is, that word will be mispronounced by thousands who will pass it on and on and on. Look what's happening to a simple word like tour.
I like your effort and your video very much. I would suggest a simpler technique to present to students: First, set the watch to GMT (of UTC, if you prefer that terminology). Then, determine the GMT (watch time) of solar noon using the method in your video. The difference between GMT and 12:00 (solar noon), in hours and decimal fractions of an hour, times 15, is your rough longitude. You could then apply the Equation of Time value for your particular date as you describe in this video to refine your longitude figure.
Absolutely the best explanation and a practical demonstration of how to find a longitude position based on a chronometer set to GMT, and a needle casting a shadow on a sunny day. Even I understood the science behind it. Thank you.
But how do you determine your longitude when you are for example in the middle of the ocean and do not know your position at all. That is exactly what you want to find? And what role does the chronometer play in this. This video unfortunately does not provide an answer to this... Where can I find an answer to this?
Outstanding! What a legacy we have and great respect for those from millennia ago.
As always … "Education" … is where you find it!
I thank you for this 'gem' .. :)
Only two marks are enougth to find solar noon
Put mark at 10:30 and draw circle arc from it using pin as center.
Then wait until shadow touches this arc at evening (shadow is same length as at 10:30)
Put second mark. Draw an line between marks an find the middle point on it. Line between pin top and that middle point will be precisely south-north aligned.
Time when shadow points to south (or north if you're in Southen hemisphere) you can calculate easily - it is a middle of time range between timestamps of two marks on arc
Yes. That was one of the Boy Scout methods of finding true north. At the moment the shadow points true north is also local solar noon.
Idiots in the disUnited states are contemplating permanent daylight savings time, basically moving everything 15 degrees east. Local solar noon would be 1100 rather than 1200 (approximately).
Nice treatment of the subject. I used two nails oriented perfectly N/S and recorded the time of perfect shadow alignment. This of course required a perfect N/S line. Then I applied the equation of time as you did. I like your method better. ;-)
What an incredibly informative video! Thank you. This should be taught in all schools!
TH-cam is a gift to mankind.
A complex problem, beautifully and simply described.
This is a great video.
I think it would have been better at 7:02 to demonstrate longitude calculation from solar noon as they had done in the past at sea. i.e. set your watch to Greenwich Time, as they would have done before leaving port in England.
Then you wouldn't have to explain that you are in America which is 5 hours behind etc... prior knowledge you wouldn't have if you were lost at sea.
Watch the ball fall at Greenwich!
Totally agree. The video missed the point.
That is the reason he said chronometer dude... a watch measures time where you are a chronometer keeps time elsewhere it is the comparison of solar noon at TWO different LOC's at the SAME TIME that allows us to use this constant to determine the distance (a variable as you travel N & S from equator to poles) in an E- W or W- E direction... it is precisely because of this fact that a clock-maker was the one to solve the riddle... you can't measure the variable distance directly.... but you can measure the constant of the earths travel around the sun... a time solution to a variable distance problem!
I was a squad leader in the Army and taught land nav to young soldiers. Many couldn’t read a map if there life depended on it. Without a cell phone they would be in trouble.
Rick A.
Wonder if any of them know the difference between their and there? You obviously don’t.
Cell phones didn't have GPS when I was in... which is why I would bring a Garmin eTrex! With few exceptions people live and fight in cities so arguably aerial imagery is more important than topo maps. SF probably has the most need for traditional orienteering/land nav and they'll use GPS if available.
I read in Navy Times last year, that the Navy is going back and teaching their officers how to navigate this way as they used to do with a Sextant. The reason was a good one too. In case their navigation satellites get taken out by the enemy.
Take it easy Scotch Terrier. We are all here because we like to learn things. No need to snap at the guy. He had a valuable contribution to make to the conversation. @@Scottie1152
@@alexgilchrist6262 I guess he got butt hurt. Probably triggered cuz he cant (not "to lean") reed a map.
I'm currently reading the Dava Sobel book and this video provides a very practical visual explanation of the calculation of longitude.
Thank you
Im glad you put some perspective in there. The fact a small error (to most people) can give you a 80km variation really drives home how precise you need to be.
Excellent learning information and history!
Flat earth believers must really enjoy this video..... 🤣🤣🤣🤣
Oh Yeah !! Too bad it could of offered some practical information, but left out a very important detail !
This world is STATIONARY and FLAT !!
SORRY TO CAUSE YOU A LITTLE DISTRESS !!!!!
Jim Petosa Don't worry...I think they're just a bunch of trolls, with maybe a few mistaken and ignorant extremists they allow among them for appearances.
@@brianharrigan8821 No distress Brian, just one question.
If the world is flat as you reckon, and North is North,
Why cant i see Polaris (The North Star) from my place on this globe?
I'll leave it to you to reply before i tell you where i live :) Peace.
Ps. No need to raise your voice( CAPS) it makes you appear desperate and forceful and in a panic to make people see your way. Peace.
Reaper4367 flatards and fundys have a belief and then invent evidence to support their beliefs, the opposite to science, observation and reason and logic... blah blah blah... nothing wrong with skepticism... science changes as it grows unlike ridiculous beliefs...’ it is easier to fool someone than to convince someone they are wrong....’ have a great day....
@@brianharrigan8821 What would be the difference if the earth was stationary and the stars were moving? There would be no difference in the calculation. If you weren't taught that the earth was moving, you would think the stars are moving. Example; you may have run across this before...this happened to me which made me think about the problem of which is moving. You are sitting in your car at a red stop light. You aren't really paying too much attention, you're just waiting. The next thing you know, you are rolling backwards; you push harder on the brakes but that doesn't help. you think your brakes are failing. Then you realize the car next to you is inching ahead and you are not moving at all. This whole scenario takes about 5 seconds. Because the only reference point was the car beside you, you can't tell which is moving. So if you were taught that the stars were moving and the earth is stationary, you could believe that as you can't feel any movement. It all depends on what you were taught in this case. That's why the ancient civilizations, who built the mega structures, that we can't duplicate today, proves they were not stupid but highly intelligent and they believed the earth was still and the stars were moving. You would too except someone told you different and because you think they are more intelligent than you, you believed the first thing you heard as being true. Santa is not real to you today (I'm assuming) BUT HE WAS because someone told you he was. Then someone told you he wasn't and so now he's not. Why do you believe one and not the other when you can't prove either. You yourself can't prove the earth is round, you are relying on the information you're given and if you believe that your government doesn't lie and NASA isn't lying, then the earth is round. However, we know now that there is great controversy in the scientific community because many things NASA is stating are not adding up, just as scientists and engineers in many countries are finding many problems with the so called "facts" that planes brought down the Twin Towers and an invisible plane must have hit the Pentagon because they can't find any plane parts, bodies, seats or luggage. So believe what you want if you trust the information is true and the only way to find the truth is to look at EVERYTHING whether you believe it or not and try to find out why others believe what they do. Test both sides if you want the truth and listen to nobody. Just because something is popular, doesn't mean it is true; it just means it's popular, today; but somewhere down the road something else may take its place because more evidence has surfaced. Think of how many times scientists have been wrong. I don't know if the earth is flat or round because I haven't seen it but what I do know, is that NASA and Al Gore are liars and you can take that to the bank.
I don't care how he pronounces longitude, we all know what the heck he means.
I learned something today, how about you?
indeed, the importance of keeping time.
clearly the religious zealots weren't navigators
How many times can you listen to it mispronounced? Just wonderin'.
BTW I learned nothing!
I agree, pronunciation is variable. Great video this!.
His recommendation about Dava Sobel's Book is a good one, it is a fantastic story of struggle and endeavour. I was born in Rochester Kent (England) and there is a link between the Longitude story and the drive to seek a solution to the problem. That reason is a clock that still hangs above the Corn Exchange near Rochester High Street was donated by Sir Cloudesley Shovell, (one time Mayor of Rochester and English Admiral) who in 1707 lost his life and four warships plus est 2,000 lives in a storm off the Scilly Isles. One major factor in the disaster was reckoned to be lack of accurate position knowledge by navigators. This lead the British Admiralty to seek ways of better determining the position on the globe. In turn this lead to 'The Longitude Act of 1714' and in turn the competition was on to devise the best seaworthy chronometer. I believe the whole thing took several decades.
@@stephenrose8188 Good Post.
Thanks for sharing.
Agreed. That makes it a Great day in my book. Share the joy!
Excellent video doing what real teachers do--make the complex accessible if not simple. BTW, the man is Canadian as his pronunciation of other words makes clear. Canadians are too polite to point out ignorant boors in the comments section who don't understand that there are many perfectly correct dialects of English in the world.
That was an excellent and fascinating video. Your use of graphics to demonstrate what was going on was masterful. Thanks for taking the time to produce this video. I have added it to my favorites list.
Thanks for taking the time to explain. Very useful.
Well done. Clear and well told.
In the comments section it seems once more that English speaking persons think they invented language itself. Nothing wrong with the pronunciation of "longitude".
The pronunciation of "data", however, is questionable.
But I would rather acknowledge the video of this dude.
YES YES, acknowledge and promote this and others like it. Thanks!
One of the most interesting and worthwhile things I have found on the internet. Thanks
I did this experiment about 10 years ago, using a quadrant (latitude), and watch (longitude). The chart for equation of time and declination, was available in an old air force survival manual. At the time there was no TH-cam videos, so I made one, but needed to correct some things to make it easier to understand. Never got around to re uploading, but I love this video. Very clear and good instructions. Thank you!
stellar explanation! Made geography more interesting.
ha. I see what you did there!
Nice Video - really easy to follow and get the idea of finding longitude
sad they don't teach this anymore. Many people cant read a map.
You cant read a map, it is not a book, maps get deciphered.
I was about to say the same thing. It's pathetic the amount of education one gets in America these days (on average) for 12 years of schooling.
Rohn Daughtry \
Many people now cannot read an analog clock! If'n it ain't digital they don't know what time it is!
@@Jimwill01 It is PATHETIC. Can you imagine what this world will be like when these are the people running things? They don't even teach cursive in America. I've asked lawyers "What's going to happen when these people can't read the founding documents of this country?" They don't even know how to answer.
This professorial lecturer in Astronomy approves this very good and simple explanation of getting one's longitude.
But how do you determine your longitude when you are for example in the middle of the ocean and do not know your position at all. That is exactly what you want to find? And what role does the chronometer play in this. This video unfortunately does not provide an answer to this... Where can I find an answer to this?
Wonderful ! I was a Geography major in College, so this is very interesting to me. Longitude I knew was time based. I have often timed the Moon’s progress across the sky. I figured out why there was 360 in a circle, and why there is 24 hours in a day ( stick and string, radius, and 12 points, etc) 60 minutes in an hour, etc. Primitive, I know, but so revealing why things are the way they are. Thanks!
Interesting that degrees are split into minutes and seconds; sorry I am probably going round in circles.
Amazing channel with perfect animations, kudos
Fascinating history.
Most people say longeetude, it is odd to hear longuetude.
Very nice. But the use of the clock is not explained clearly. I imagine sailers set out from “Greenwich” and set their clock at 0:00 or 12:00. They did not change this during their voyage. In other words, they carried Greenwich time with them. At any point on earth they knew what time it was in Greenwich. A precise clock was thus of paramount importance.
That's the reason he said chronometer dude... a watch keeps your time a chronometer keeps time in another place...based upon SOLAR NOON
It's nice to see this wrapped up in a short and straightforward video. A couple years ago, I purchased a sextant and book on celestial navigation. I also have a book on using the sextant. It is a remarkably elegant instrument. In the hands of an expert, the sextant I got, a Davis Mark 25, the vernier drum is marked to 2 MOA. That's equivalent to two nautical miles by definition. I imagine an expert can improve on that with multiple readings. This is certainly good enough for crossing the Atlantic because it lands you in line of sight of your port of call.
Same here and I also haven't done a thing with them except use them as doorstops as well.... gdamn TRENDS!
I never understood what role clocks (chronometers) played in navigation but I knew it was key. This video really cleared that up. Amazing, thanks science online :) That's been niggling at me for ages
Most complicated thing explained in a simplest way.
Great video Very clear explanations Thanks
Excellent video, clear and concise. Today's high school students should turn off their phones and get out in the sun with a clock! And the ancient mariners calculated latitude and longitude on the rolling deck of a square rigger. Now that's true seamanship!
From 1971 onward my best friend was the grandson of the inventor of the Weems system of navigation. I'm recalling countless sextants and other such gear, learning the basics of use. Captain Phillip V.H. Weems, USN retired had invented the system which, I was told, was in use on Apollo 11. Really amicable and brilliant man, he'd ridden on horseback from Clarksburg, Tennessee to attend the US Naval Academy in Annapolis, Maryland. I think I was in 7th grade/age 12-ish when I first met him. As we sat eating breakfast, hearing wonderful stories of his travels and youth, he'd pushed his plate aside, eating from my plate; a little dementia evident, but what a life of achievements. I know a land surveyor who uses Weems' equipment in celestial navigation methods.
In case anyone is confused by the pronunciation of *longitude,* you should know there are two common ways to pronounce the work. The narrator was actually using the UK pronunciation even though he lives in the US.
Thanks for the interesting video.
beautifully explained in a concise and simple way - great for the curious child to play and learn with!
I've been reading some of the comments and I have a question. How many times do I have to do a head dive into an empty swimming pool before I start to see and understand the logic of the flat earthers?
Oh, as a giggle, I surmise...maybe just once?
It's 3 actually...The same as "The Number Of licks it takes To Get To The Center Of A Tootsi-Roll Pop", according to some "Wise Old Owl" th-cam.com/video/IBwJHXqryh0/w-d-xo.html
Awesome video. Great work!
FYI, Dava Sobel is a woman. She has authored several books related to Astronomy. I enjoyed your video very much!
Great video presentation with superb explanation. Now I understand what all the degrees mean and can picture this. Thank you.
Flat earthers disapprove this video.
Not a flat earther, but please practice what you preach. Don’t make fun of people for no reason.
@@FemboyEngineerwhy
@@FemboyEngineerno reason ? Ppl 4 hundred years ago figured out that the earth is round , today with the advanced technology we have now we actually have ppl arguing a subject that was resolved hundreds of years ago . So no good reason ? 😂 They should be laughed at for challenging something for just the sake of challenging something
@@easternsuneasternsun171 um, actually, no. People did not prove the Earth was round 400 years ago. That’s a bit silly to think it took us that long.
It was proven about 2,500 years ago by the Greeks by measuring distances, celestial bodies, and light and shadows. They even accurately calculated the circumference (how big it is, calculating the distance it would take if you traveled all the way around in a straight line and back to where you began). Eratosthenes’ estimate was only about 300 miles short of the actual circumference.
I think you were referring to circumnavigation, sailing around the world. It isn’t necessary to circumnavigate to prove the earth’s roundness. People think Columbus proved the earth was round. He didn’t. A flat earther would argue that by reaching the Americas he simply showed that the planet is larger than previously imagined.
It was actually Magellan who first sailed around the world. Again, this didn’t prove the earth was round (I mean, yes, it is another bit of evidence for it) because it was already known to be round and sailing coordinates were estimated based on the model of a round earth.
@@easternsuneasternsun171bravo
Perfectly explained. Thank you.
Interesting you say LONG uh too d. I've always said LONJ uh too d. I read the book long ago and there was a great PBS series on this. I think that this should be taught for a couple of days in high school. Maybe even before geography..which I guess they don't teach anymore :-(
Great presentation. I recently visited the Lewis and Clark museum near me and they had a demo of how they would find their location using the mercury method and sextant. Noon sights of course, for the most part.
Finally. Someone asked why he pronounces "longitude" the way he does. I, too, have always heard it pronounced "lonJ-ih-tude." I wish the creator of the video or someone else had responded to you. Nothing I found in a quick search via Duck Duck Go explains it.
It creates the impression of incompetence, making the listener slightly skeptical that he really knows what he is talking about.
Yes, (at anyone misreading what I just wrote) he IS competent and demonstrates this, but, the mispronunciation (or odd and unusual pronunciation
Impressive and satisfying project. Very well done.
Great, simple, understandable explanation - thank you for posting!
Thank you sir! you explained it really well.
I love these educational videos. How does daylight saving time affect this, or how do we compensate for it?
I'm pretty sure you would just deduct an hour in DST.... not 100% sure though.
+emory edmunds the first nationwide implementation of DST was only in 1916. Which is well past the golden age of naval exploration.
+wvb93 I was referring to using this method now. Thanks.
Woods Tramp - We always keep track of time using Greenwich mean time which doesn’t change with DST.
I loved this video: thank you!
Very good and instructive video.. I really enjoyed watching this explanation.. Thank you very much !
This is an outstanding explanation of a complex subject. Congratulations on achieving such good accuracy with simple tools. I'm impressed.
Hate to tell you. It's not a complex subject